GH 1960 & GH-2028 ForgotPassword Hub Error Message and Loading Icon Fix

[benstrumeyer]

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This PR addresses GH-1960 kickbacks

• Forgot Password cancel button in the hub now redirects to log in screen
• A toast is shown when a user enters an email we don't have in our system
• Move loading icon scss to a partials directory to be used in panel and hub

Tickets:

• https://cliqztix.atlassian.net/browse/GH-1960
• https://cliqztix.atlassian.net/browse/GH-2028

[Eden12345]

I know this was not part of this PR, but I noticed when testing this that the design of the Forgot Password view is completely out of sync with the rest of the Account views in the Hub. See the screenshots below for reference.

Sign In view (an example of the correct design pattern for the Hub):

Forgot Password view (button colors are wrong, the input field has the wrong border radius and box shadow, the loading state changes the size of the submit button, and it isn't centered in the view overall):

Since this wasn't what this PR was made for, as with my other comment I don't think it should stop this PR from being merged. I do think, though, that we should make an improvement ticket if there isn't already one. The CSS classes and components are already created that follow the correct design pattern, so I wouldn't think this would be a very major undertaking.

[Eden12345]

I know this wasn't added in this PR either, just wanted to point out that it's a rather confusing choice semantically to use "locale" for the variable name for which view we're in when we also have locales for translations.